1. Technical Field
The present disclosure relates to detection of improvised explosive devices and other devices.
2. Description of Related Art
The control electronics in Improvised Explosive Devices (IEDs) typically rely on radio frequency (RF) transmitters and receivers. These components can be readily obtained through exploitation/disassembly of mass market electronics, such as RF-emitting garage door openers, cell phones, automotive key-fobs, etc. As apparatus and methods are developed to counter RF-based IEDs, builders of such devices will naturally transition to alternative control electronics.
One possible alternative is optical control systems. The IED could include a silicon photodetector that would detect an infrared (IR) beam. These systems could be based on simple modifications of IR-transmitting remote controllers. For example, it would be very simple to replace the light-emitting diode (LED) in the IR remote control systems commonly incorporated in TVs and other consumer electronics with a semiconductor laser emitting at an IR wavelength compatible with the control unit receiver. The resulting IR remote control system would have a much larger standoff distance capability, due to the far narrower laser beam divergence.
As makers of IEDs transition from controllers that are RF-based to those that are optically controlled, new challenges in locating these IEDs and neutralizing them will arise. Detection of the IR remote control receiver system is difficult due to the small size of photodetectors, the dynamic nature of the IR ambient environment, and wide variations in IR reflectivity from other background objects. While multispectral and hyperspectral imaging systems (e.g., acousto-optic tunable filter (AOTF) based video imaging systems) could be used to detect Si-based photodetectors in principle, the imaging rates would be too slow or have insufficient resolution to be useful. Other detection schemes have been used to identify video camera systems in environments of interest, such as in movie theatres to defeat unauthorized recording of movies. However, the approaches used to detect video cameras, essentially on the basis of physical optics (lens) detection, do not represent a viable solution to detecting optically-controlled IEDs.